Astrology basics
The foundational concepts of Western astrology (signs, planets, houses, and aspects) explained as a reader-friendly reference.
The concepts every chart reader leans on. New to astrology? Start here, and the terms that show up across the feature pages will land much more smoothly.
A chart is built from four layers: signs, planets, houses and aspects. The four pages below explain them one layer at a time, in that order.
Zodiac signs The 12 signs from Aries to Pisces and what each one carries.
Planets What each celestial body, Sun through Pluto, represents.
Houses The chart divided into 12 areas of life, and how to read them.
Aspects The angular relationships between planets and what each type means.
Terms used in these docs
The docs and the app use these words in the same way. Come back here if you are unsure.
| Term | Meaning |
|---|---|
| Natal chart | The chart of the sky at the moment of birth. Also called a horoscope or simply a chart |
| Single wheel | The natal chart drawn as one circle |
| Triple wheel | The natal chart with the current sky (transit) and the progressed chart laid over it |
| Synastry | The screen that lays two people’s natal charts over each other |
| Ascendant (ASC) | The sign and degree on the eastern horizon at birth. On Home it appears as “How you come across” |
| DSC | The point opposite the ASC, on the western horizon |
| MC (Midheaven) | The point where the meridian meets the ecliptic, to the south |
| House | One of the 12 areas of life the chart is divided into. Counted as “1st house”, “2nd house” and so on |
| Cusp | The boundary line of a house |
| Degree | A position within a sign, from 0° to 30° |
| Orb | How far an aspect may stray from the exact angle |
| Major planets | The ten bodies from the Sun to Pluto |
| Sensitive points | Calculated points such as the North Node and Lilith |
| Arabic Parts | Points worked out from the positions of several bodies and points. Also called lots |
| North Node / South Node | The two points where the Moon’s orbit crosses the ecliptic. |
| Element | The four groups: fire, earth, air and water |
| Modality | The three groups: cardinal, fixed and mutable |
| Transit | The positions of the planets in the sky now. On the triple wheel the ring is labeled “Transit” |
| Progressed | Positions advanced by one day for each year of life. On the triple wheel the ring is labeled “Progressed” |
| Void | Short for void-of-course Moon: the time until the Moon enters the next sign without making a major aspect |
| Soft / hard | A grouping of aspects. Soft means trine and sextile; hard means square and opposition |
| Placement | Which sign and house a body is in |
| Default | The settings you have when you have changed nothing. See Default settings and calculation basis |